Statistics
posted by Adria on .
In a distribution of 400 response times with a mean of 7 minutes and a standard deviation of 2 minutes, the maximum number of response times greater than 13 minutes would be about:
A. 40
B. 100
C. 75
D. 90

According to
http://davidmlane.com/hyperstat/z_table.html
the probability of a time greater than 13 minutes is .00135
None of your choices result from that probability. 
Z = (x  μ)/SD
Z = (137)/2 = 6/2 = 3
Look up this Z in a table in the back of your statistics text covering areas under the normal distribution for the smallest area. Multiply this value by 400.
Unfortunately, that does not fit any of your choices. Do you have any typos? 
No. No typos. That's how its written on the packet I am doing. Thank You so much for your help though, I guess my teacher might've made a typo...

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